This is 's character, an OC pegasus named Mimi Cloak (or Mimic for short).
The concept and names are hers, I only designed it after she suggested it!
She is able to change the color of her mane according to her emotions. Each emotion is one of the colored tip of her mane, making the white take that color.
Cutie mark and pet are a chameleon.
Mlp (c) Hasbro, Lauren faust